Remove the review bot app.

reviewbot/handlers/policy_checklist/modification_comment.txt

Index: reviewbot/handlers/policy_checklist/modification_comment.txt
===================================================================
--- reviewbot/handlers/policy_checklist/modification_comment.txt	(revision 221173)
+++ reviewbot/handlers/policy_checklist/modification_comment.txt	(working copy)
@@ -1,17 +0,0 @@
-When modifying an existing policy setting, please consider the following:
-
-- Make sure the policy meta data is up-to-date, in particular
-  supported_on, and the feature flags.
-- In general, don't change policy semantics in a way that is
-  incompatible (as determined by user/admin-visible behavior) with
-  previous semantics. In particular, consider that existing policy
-  deployments may affect both old and new browser versions, and both
-  should behave according to the admin's intentions.
-- It is OK to expand semantics of policy values as long as the previous
-  policy description is compatible with the new behavior.
-- It is OK to update feature implementations and the policy description
-  when Chrome changes as long as the intended effect of the policy
-  remains intact.
-- The process for removing policies is to deprecate them first, wait a
-  few releases (if possible) and then remove them. Make sure you put the
-  deprecated flag if you deprecate a policy.